The Tardis coin will be revealed in Berlin at the World Money Fair. Mr Harding didn't have one to flaunt for the camera, because the coins are currently "hidden away in a vault in Berlin".

If you're a fan of the time-travelling, shape-shifting alien, nabbing a Tardis coin will set you back $155 – and Mr Harding's advice is not to spend it. Its value – much like the Tardis – is much bigger on the inside than the out.

"It's worth $2 in Niue if you choose to spend it, so I wouldn't advise that as an investment."

But you'd better get in fast, as only 10,000 will be made before the run is – if you'll excuse the pun – exterminated.

"So come what may, you cannot buy more than 10,000 of these coins," says Mr Harding, "and we're quietly optimistic that there won't be too many left later in the year."

The 11 coins featuring each of the Doctors will be released later in the year.

New Zealand was the first country outside of the UK to screen Doctor Who, with broadcasts beginning in September 1964.